ZHCSH31B August 2017 – February 2018 DRV10987
For any given motor, the integrated value of BEMF during half of an electrical cycle is constant. The value is determined by the BEMF constant (Kt) (see Figure 36). The BEMF constant is the same regardless of whether the motor is running fast or slow. This constant value is continuously monitored by calculation and used as a criterion to determine the motor lock condition, and is referred to as Ktc.
Based on the Kt value programmed, create a range from Kt_low to Kt_high. If Ktc goes beyond the range for a certain period of time, tLCK_ETR, lock is detected. Kt_low and Kt_high are determined by KtLckThr[1:0] (see Figure 37).